386 
SURGERY AND TRANSPLANTATION 
Table II. — pH, Blood Gases and Oxygen Saturations (Mean ± SD) During LVAD Pump Implantation in Calves 
Using JPBB (Two Ventilatory Pressures) 
surgical manpulation 
arterial 
chest 
left of lung 
chest 
spontaneous 
cannulation 
open 
retraction of 
closure 
breathing 
IPBB 
Face Mask 
+ 
40% 
100% 
O2 5 L/min 
7.50 
7.54 
7.48 
7.45 
7.43 
7.39 
7.4 
7.39 
N = 8 
PH 
±0.03 
±0.03 
±0.01 
~^0 04 
±0.01 
±0.02 
±0.01 
pCOs, mm Hg 
35.1 
32.5 
35.0 
38.6 
42.1 
40.4 
39.4 
48.2 
Q 
±1.2 
±1.7 
±5.5 
±5.0 
±6.9 
±3.4 
±3.7 
±5.0 
P s 
pOs, mm Hg 
164. 
154 
112.0 
80.5 
77.5 
112.4 
82.5 
69.4 
« m C 
±22 
±26 
±13.0 
±12.0 
±7.1 
±15.7 
±18.0 
±12.0 
c 0 
O3 
97.5 
97.3 
94.8 
94.1 
93.6 
96.3 
90.5 
92.8 
CJ Qj 
> ^ 1 
^ \a 
±0.3 
±0.2 
±2.4 
±1.4 
±0.5 
±0.2 
±2.5 
±4.0 
i-t 
7.49 
7.44 
7.45 
7.42 
1.45 
7.42 
7.32 
7.48 
N = 5 
pH 
±0.02 
±0.09 
±0.03 
±0.05 
±0.08 
±0.07 
±0.07 
±0.03 
PCO2, mm Hg 
24.9 
37 
32.5 
30.7 
28.9 
30.7 
32.8 
35.9 
±0.8 
±3.9 
±4.3 
±4.1 
±2.5 
±4.1 
±3.8 
±2.0 
s ^ ^ 
pOa, mm Hg 
271 
181 
170.3 
167 
228 
238 
203 
113.9 
^ m £ 
±42 
±26 
±6.6 
±28 
±28 
±28 
±13 
±9.0 
C i-« 0 
O2 
97.6 
97 
96.6 
96.8 
96.7 
97 
97 
96.6 
^ 0 
±0.3 
±0.3 
±0.5 
±0.3 
±0.2 
±0.2 
±0.2 
CO 
30-40 cmHsO resulted in significant (P < 0.01) 
increases in tidal volume and pOo. 
Conflicting reports have appeared with re- 
gard to optimal ventilatory pressures in the 
calf. Larson et al./*' working with young calves 
weighing less than 15 kg reported that pres- 
sures about 10 cm HgO caused rupture of al- 
veoli and extensive pulmonary hemorrhage. 
With these possibilities in mind, several investi- 
gators have used lower pressures than those 
employed in our second group of animals in 
calves weighing between 61 and 110 kg. Dona- 
wick et al. found that pressures above 30 cm 
H2O were necessary to prevent atelectasis and 
maintain adequate oxygen pressures during 
sham thoracotomies, while pressures below 20 
cm H2O resulted in hypoxia, hypercapnia, and 
atelectasis.^^ Our experience with high inspira- 
tory pressures has been similar. The efficacy of 
high pressures might be explained by the find- 
ings of McLaughlin and associates'^ who re- 
ported on the well-developed lobularity of the 
calf lung, the thick inelastic pleura, the poorly 
developed respiratory bronchioles, and the pres- 
ence of bronchopulmonary anastomoses. 
An additional mechanical factor necessitating 
higher inspiratory pressures during left ven- 
tricular assist device implantation is the in- 
crease in abdominal pressure produced in left 
lateral position. This problem is frequently com- 
pounded in the calf by abdominal distention 
caused by bacterial fermentation and gas ac- 
cumulation in the rumen during anesthesia. The 
normal calf produces 60 to 80 liters of CO2 and 
methane per day^'' which accounts for the 
marked abdominal distention occasionally seen 
within a few hours after thoracotomy. Contrib- 
utory factors include loss of eructation under 
general anesthesia and the poorly understood 
bloating syndrome. Withholding of food for 24 
hours prior to surgery is not always effective in 
preventing abdominal bloating. Large caliber 
nasogastric tubes were used and proved to be 
of some value. On occasion, however, more com- 
plete decompression was necessary and was 
achieved by insertion of a 14 gauge 3" needle 
into the rumen through the left flank. Recently, 
temporary gastrostomy has been found to be 
more efficient for gastric decompression. 
An additional mechanical measure that can 
be utilized consists of increasing the resistance 
to expiration at intervals in order to increase 
functional residual volume and thus prevent 
progressive collapse of alveoli and decrease any 
degree of shunting.^i 
ANTIARRHYTHMIC REGIMEN 
The sudden occurrence of cardiac dysrhyth- 
mias and ventricular fibrillation is another ma- 
